1. Field of the Invention
The invention relates to an immersion nozzle for pouring molten metal, especially steel, from a pouring vessel into a mold of a continuous casting machine. The immersion nozzle has a substantially tubular upper part, which can be attached to the pouring vessel, and a lower part that has a broad side significantly larger than its narrow side on the opening end. In the transitional zone, the interior walls of the upper part and the lower part correspond.
2. Description of the Prior Art
In multi-part immersion nozzles, especially those in which different nozzle parts are made of different refractory-grade materials, the joint point represents a particular weak spot.
German reference DE 41 42 447 teaches an immersion pouring tube for molten steel which at its separation joint in the tube flange, has a recess into which a seal can be placed for the purpose of sealing. The immersion tube itself is flanged to the bottom plate of the casting vessel.
Disadvantageously, the connection to the casting vessel influences the joint point of the immersion pouring tube part, which otherwise is only slightly different in material.
From German reference DE-OS 37 09 188, a pouring tube for metallurgical vessels is known, which has an inlet tube with a slot into which a first holding plate is laterally inserted. A second holding plate engages below a flange of the pouring tube connected downstream in the pouring direction. The second holding plate presses the pouring tube or the flange against the end of the inlet tube by means of pairs of threaded screws.
The refractory-grade components of this immersion nozzle are complicated in form. Furthermore, the joint point is formed by materials (i.e., the metal holding screws and the spherical ends of the pouring tube parts) that differ greatly with respect to thermal expansion.
German reference DE 43 20 723 discloses an immersion nozzle in which shaped bricks engage into one another. A seal is provided between the interengaged ends of the shaped bricks. The seal is meant to prevent exterior air from penetrating between the interengaged ends of the shaped bricks and making its way into the interior space of the immersion nozzle. The seal is also meant to absorb differing thermal expansions of the shaped bricks. On the part of the immersion nozzle that faces the mold, there is a holding mechanism that is fastened underneath by elbows, so that the total of three shaped bricks of the immersion nozzle are held securely together during operation. At the other end, the holding mechanism is attached to a component that is independent of the immersion nozzle, with the disadvantage that here uncontrolled movements of individual parts of the immersion nozzle can occur.